My observations on the Phillips Island video as related to similar HP track days here in the USA:
The difference in performance seems to me more related the driver's ability and not the car they were driving.
Only a few were track prepped and I suspect on street tires, maybe even high performance tires but not race tires.
Unless you have done a lot of track days having a "race" car in your rearview mirror can cause folks to let you go by so they can concentrate on their own driving.
I race with a few vintage groups and they operate in one of two ways; specific classes based on HP and car performance (in the day in the USA such as A, B and C production SCCA cars) which run as a single group. It can also be B, C & D production with AP big block cars running by themselves or with others cars (lots of Zs , 911s and 914-6s). The other grouping is a mish mash of cars ranging from a 70 Camaro, a 911, a 930 turbo, 240/26/280 Datsun Zs, an Alfa GT V6, a Shelby GT350 Mustang, IMSA corvette, a 65 Barracuda or a Datsun 510. Each is in a different subgroup but on the track racing at the same time. My 72 Datsun with a fully race prepared L28 is only 2-7 seconds off the pace depending on the track and conditions (wet vs dry). As a Datsun driver I admit to getting a kick out of beating a Porsche (when I can) in the same manner that Bob Sharp, Sam Posey and Jim Fitzgerald did in their Datsuns. I use the later rear spoiler from the Sharp #33 car to remind a Porsche driver who's in front of them.....